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Herbaceous Perennial

Delphinium 'Clifford Sky'
  • RHS AGM

delphinium 'Clifford Sky'

'Clifford Sky' is a tall perennial with white-eyed, semi-double sky-blue flowers 7cm across, in branched spikes in summer

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Size
Ultimate height
1.5–2.5 metres
Time to ultimate height
2–5 years
Ultimate spread
0.5–1 metres
Growing conditions
Chalk
Loam
Sand
Moisture
Moist but well–drained, Well–drained
pH
Acid, Alkaline, Neutral
Colour & scent
StemFlowerFoliageFruit
Spring Green
Summer Blue White Green
Autumn Green
Winter
Position
  • Full sun
Aspect

West–facing or South–facing or East–facing

Exposure
Sheltered
Hardiness
H5
Botanical details
Family
Ranunculaceae
Native to the UK
No
Foliage
Deciduous
Habit
Columnar upright
Potentially harmful
All parts may cause severe discomfort if ingested and may irritate skin. Wear gloves and other protective equipment when handling
Genus

Delphinium can be annuals, biennials or perennials, with palmately lobed basal leaves and showy bowl-shaped flowers in spikes, racemes or panicles

Name status

Accepted

How to grow

Cultivation

Grow in a fertile, well-drained soil in full sun; shelter from strong winds and stake well. Apply a balanced liquid every couple of weeks in the growing season. For the best flower spikes thin shoots when 7cm high to leave a minimum of 2-3 shoots on young plants and 5-7 shoots on established plants

Propagation

Propagate by taking pencil thick basal cuttings in early spring

Suggested planting locations and garden types
  • City and courtyard gardens
  • Cottage and informal garden
  • Cut flowers
  • Flower borders and beds
Pruning

Deadhead by cutting spent flower spikes back to small flowering side shoots. Cut down all growth to ground level after it has withered in autumn

Pests

May be attacked by slugs, snails, leaf miners and caterpillars

Diseases

May be subject to powdery mildews, delphinium black blotch, crown rot and a virus

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